Check the appropriate box below if the Form 8-K
filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see
General Instruction A.2. below):

¨

Written communications pursuant to Rule 425 under
the Securities Act (17 CFR 230.425)

Indicate by check mark whether the registrant
is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2
of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company
¨

If an emerging growth company, indicate by
check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial
accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 4.01. Changes in Registrant’ Certifying Accountant

Effective November 16, 2017, Hein & Associates LLP (“Hein”),
the independent registered public accounting firm for Real Goods Solar, Inc. (the “Company”), combined with Moss Adams
LLP (“Moss Adams”). As a result of this transaction, on November 16, 2017, Hein resigned as the independent registered
public accounting firm for the Company. Concurrent with such resignation, the Company’s audit committee approved the engagement
of Moss Adams as the new independent registered public accounting firm for the Company.

The audit reports of Hein on the Company’s financial statements
for the years ended December 31, 2016 and 2015 did not contain an adverse opinion or a disclaimer of opinion, and were not qualified
or modified as to uncertainty, audit scope or accounting principles.

During the two most recent fiscal years ended December 31, 2016
and through the subsequent interim period preceding Hein’s resignation, there were no disagreements between the Company and
Hein on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedures, which
disagreements, if not resolved to the satisfaction of Hein would have caused them to make reference thereto in their reports on
the Company’s financial statements for such years.

During the two most recent fiscal years ended December 31, 2016
and through the subsequent interim period preceding Hein’s resignation, there were no reportable events within the meaning
set forth in Item 304(a)(1)(v) of Regulation S-K.

During the two most recent fiscal years ended December 31, 2016
and through the subsequent interim period preceding Moss Adam’s engagement, the Company did not consult with Moss Adams on
either (1) the application of accounting principles to a specified transaction, either completed or proposed; or the type of audit
opinion that may be rendered on the Company’s financial statements, and Moss Adams did not provide either a written report
or oral advise to the Company that Moss Adams concluded was an important factor considered by the Company in reaching a decision
as to the accounting, auditing or financial reporting issue; or (2) any matter that was either the subject of a disagreement, as
defined in Item 304(a)(1)(iv) of Regulation S-K, or a reportable event, as defined in Item 304(a)(1)(v) of Regulation S-K.

The Company has provided Hein a copy of the disclosures in this
Form 8-K and has requested that Hein furnish it with a letter addressed to the Securities and Exchange Commission stating whether
or not it agrees with the Company’s statements herein. A copy of the letter dated November 17, 2017 is filed as Exhibit 16.1
to this Form 8-K.